Production of C2 toxin by Alexandrium tamarense CI01 using different culture methods

The dinoflagellate Alexandrium tamarense CI01 was grown in three types of cultures: batch culture, semi-continuous culture and temporary culture, to investigate the effects of different culture methods on cell growth and the productivity of C2 toxin (C2, a paralytic shellfish toxin). In the batch cultures, cells grew in three phases: a short lag phase, an exponential phase with a specific growth rate ( mu ) of 0.78 day super(-1) and a relatively long stationary phase. The maximum toxin productivity was 1.2 mu mol L super(-1) or 77 fmol cell super(-1) in 9 days. In the semi-continuous cultures, cells grew in response to the dilution cycles, with mu values being 0.64, 0.32 and 0.35 day super(-1) for one-day, two-day and three-day cycles, respectively. The toxin yield was about one half of that of the batch cultures. A "temporary" culture method was used to maintain the metabolically active cells removed from the semi-continuous cultures, in a nutrient-depleted condition, to achieve a high toxin productivity of 1.0 mu mol L super(-1) in 4 days. Thus, the semi-continuous culture method provided an efficient means to generate amounts of metabolically active algal cells. The temporary culture offered an effective way to produce C2. The highest yields of C2 were obtained in 3-4 days when the temporary cultures were aerated.